Mechanism of FIB-Induced Phase Transformation in Austenitic Steel

The transformation of unstable austenite to ferrite or α′ martensite as a result of exposure to Xe+ or Ga+ ions at room temperature was studied in a 304 stainless steel casting alloy. Controlled Xe+ and Ga+ ion beam exposures of the 304 were carried out at a variety of beam/sample geometries. It was found that both Ga+ and Xe+ ion irradiation resulted in the transformation of the austenite to either ferrite or α′ martensite. In this paper, we will refer to the transformation product as a BCC phase. The crystallographic orientation of the transformed area was controlled by the orientation of the austenite grain and was consistent with either the Nishiyama–Wasserman or the Kurdjumov–Sachs orientation relationships. On the basis of the Xe+ and Ga+ ion beam exposures, the transformation is not controlled by the chemical stabilization of the BCC phase by the ion species, but is a result of the disorder caused by the ion-induced recoil motion and subsequent return of the disordered region to a more energetically favorable phase.

Characterization of applied tensile stress to carbon epoxy composites by measuring the variation of transverse thermal conductivity using transmission thermography

Using the method of step heating thermography, this study seeks to detect and characterize the existence of stress in a beam sample of carbon epoxy composite with the stacking sequence of [08] aided by empirical and simulation approaches. The applied stress in the longitudinal direction of sample, while considering the Poisson’s ratio, changes the lateral dimensions of sample. Furthermore, it is shown that the thermal conductivity along the sample thickness varies as a result of stress existence. Accordingly, to obtain a relation between transverse thermal conductivity and longitudinal tensile stress, one should calculate and eliminate the effect of lateral deformation caused by stress. To this end, by combining the experimental and simulation results of composite sample under the action of different tensile loads, an equation describing the variation of thermal conductivity along the sample thickness with respect to applied stress is developed. Using the relation of transverse thermal conductivity variation in terms of applied stress, the finite element modeling is again carried out by rectifying the values of thermal conductivity. Simulation results are compared with experimental ones, indicating very good agreement between the two approaches.

PENELITIAN UJI KUAT TEKAN BETON DENGAN MEMANFAATKAN AIR LIMBAH TETES TEBU DAN ZAT ADDITIVE CONCRETE

Concrete has a weakness that is having a low tensile strength and brittle so that the concrete is given steel reinforcement to anticipate it. This addition was carried out to study and determine the effect of sugarcane waste on compressive strength, flexural strength on normal quality concrete with the addition of 0%, 10%, 20% and 30% in compressive loads. Testing is done after 28 days. Concrete with the addition of 30% sugar cane is more capable of producing high flexural strength than the others. Addition of sugar cane drops resulted in optimum compressive strength of 10%, 16.75MPa, 20%, 16.55MPa, 30%, 16.40MPa. For the highest flexural strength of concrete in the 15/15/60 beam sample, the concrete mixture was added to 30% sugar cane by 5.00 MPa, higher than normal concrete 4.96 MPa.Beton mempunyai kelemahan yaitu mempunyai kuat tarik yang rendah dan bersifat getas (brittle) sehingga beton diberi tulangan baja untuk mengantisipasinya. Penambahan ini dilakukan untuk mempelajari dan mengetahui pengaruh limbah tetes tebu terhadap kuat tekan, kuat lentur pada beton mutu normal dengan penambahan 0%, 10%, 20% dan 30% pada beban tekan. Pengujian dilakukan setelah 28 hari. Beton dengan penambahan tetes tebu 30% lebih mampu menghasilkan nilai kuat lentur tinggi dari pada yang lainya. Penambahan limbah tetes tebu menghasilakan kuat tekan optimum yaitu,10%,16,75MPa, 20%,16,55MPa, 30%,16,40MPa. Untuk kuat lentur beton pada sampel balok 15/15/60 yang paling tinggi yaitu pada campuran beton penambahan tetes tebu 30% sebesar 5,00 MPa, lebih tinggi dari pada beton normal 4,96 MPa.

Fast positioning for X-ray scanning microscopy by a combined motion of sample and beam-defining optics

Scanning X-ray microscopy such as X-ray ptychography requires accurate and fast positioning of samples in the X-ray beam. Sample stages often have a high mobile mass as they may carry additional mechanics or mirrors for position measurements. The high mobile mass of a piezo stage can introduce vibrations in the setup that will lead to imaging quality deterioration. Sample stages also require a large travel range which results in a slow positioning step response and thus high positioning overhead. Moving lightweight X-ray optics, such as focusing Fresnel zone plates, instead of the sample can improve the situation but it may lead to undesired variations in the illumination probe which may result in reconstruction artifacts. This paper presents a combined approach in which a slow sample stage mechanism covers the long distance range for a large field of view, and a light-weight optics scanner with a small travel range creates a superimposed motion to achieve a fast step response. The step response in the ptychographic tomography instrument used was thereby improved by an order of magnitude, allowing for efficient measurement without loss of imaging quality.